/* ========================================
   CSS Custom Properties & Theme
   ======================================== */
:root {
  --font-sans: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
  --font-mono: 'JetBrains Mono', 'Fira Code', monospace;

  --max-width: 1100px;
  --nav-height: 64px;

  --radius-sm: 6px;
  --radius-md: 12px;
  --radius-lg: 20px;

  --transition: 0.3s cubic-bezier(0.4, 0, 0.2, 1);
  --transition-slow: 0.6s cubic-bezier(0.4, 0, 0.2, 1);
}

[data-theme="dark"] {
  --bg-primary: #0a0a0b;
  --bg-secondary: #111113;
  --bg-card: #18181b;
  --bg-card-hover: #1f1f23;
  --bg-nav: rgba(10, 10, 11, 0.85);

  --text-primary: #fafafa;
  --text-secondary: #a1a1aa;
  --text-tertiary: #71717a;

  --border: #27272a;
  --border-hover: #3f3f46;

  --accent: #6366f1;
  --accent-light: #818cf8;
  --accent-glow: rgba(99, 102, 241, 0.15);

  --gradient-start: #6366f1;
  --gradient-end: #a78bfa;

  --tag-bg: #1e1b4b;
  --tag-text: #a5b4fc;

  --badge-bg: rgba(34, 197, 94, 0.1);
  --badge-text: #4ade80;
  --badge-dot: #4ade80;
}

[data-theme="light"] {
  --bg-primary: #ffffff;
  --bg-secondary: #f4f4f5;
  --bg-card: #ffffff;
  --bg-card-hover: #f9f9fb;
  --bg-nav: rgba(255, 255, 255, 0.85);

  --text-primary: #18181b;
  --text-secondary: #52525b;
  --text-tertiary: #a1a1aa;

  --border: #e4e4e7;
  --border-hover: #d4d4d8;

  --accent: #4f46e5;
  --accent-light: #6366f1;
  --accent-glow: rgba(79, 70, 229, 0.08);

  --gradient-start: #4f46e5;
  --gradient-end: #7c3aed;

  --tag-bg: #eef2ff;
  --tag-text: #4338ca;

  --badge-bg: rgba(34, 197, 94, 0.08);
  --badge-text: #16a34a;
  --badge-dot: #16a34a;
}

/* ========================================
   Reset & Base
   ======================================== */
*, *::before, *::after {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
  scroll-padding-top: var(--nav-height);
}

body {
  font-family: var(--font-sans);
  background: var(--bg-primary);
  color: var(--text-primary);
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  transition: background var(--transition), color var(--transition);
}

a {
  color: inherit;
  text-decoration: none;
}

ul { list-style: none; }

.container {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 24px;
}

/* ========================================
   Navigation
   ======================================== */
.nav {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  height: var(--nav-height);
  background: var(--bg-nav);
  backdrop-filter: blur(16px);
  -webkit-backdrop-filter: blur(16px);
  border-bottom: 1px solid var(--border);
  z-index: 1000;
  transition: background var(--transition), border var(--transition);
}

.nav-inner {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 24px;
  height: 100%;
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.nav-logo {
  font-size: 1.25rem;
  font-weight: 800;
  letter-spacing: -0.02em;
}

.nav-logo .accent {
  color: var(--accent);
}

.nav-links {
  display: flex;
  gap: 32px;
}

.nav-links a {
  font-size: 0.875rem;
  font-weight: 500;
  color: var(--text-secondary);
  transition: color var(--transition);
  position: relative;
}

.nav-links a::after {
  content: '';
  position: absolute;
  bottom: -4px;
  left: 0;
  width: 0;
  height: 2px;
  background: var(--accent);
  transition: width var(--transition);
}

.nav-links a:hover {
  color: var(--text-primary);
}

.nav-links a:hover::after {
  width: 100%;
}

.theme-toggle {
  background: none;
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  padding: 8px;
  cursor: pointer;
  color: var(--text-secondary);
  transition: all var(--transition);
  display: flex;
  align-items: center;
  justify-content: center;
}

.theme-toggle:hover {
  color: var(--text-primary);
  border-color: var(--border-hover);
}

[data-theme="dark"] .icon-moon { display: none; }
[data-theme="light"] .icon-sun { display: none; }

.nav-mobile-toggle {
  display: none;
  flex-direction: column;
  gap: 5px;
  background: none;
  border: none;
  cursor: pointer;
  padding: 4px;
}

.nav-mobile-toggle span {
  display: block;
  width: 22px;
  height: 2px;
  background: var(--text-primary);
  border-radius: 2px;
  transition: all var(--transition);
}

.mobile-menu {
  display: none;
  position: fixed;
  top: var(--nav-height);
  left: 0;
  right: 0;
  background: var(--bg-nav);
  backdrop-filter: blur(16px);
  -webkit-backdrop-filter: blur(16px);
  border-bottom: 1px solid var(--border);
  padding: 16px 24px;
  z-index: 999;
  flex-direction: column;
  gap: 12px;
}

.mobile-menu.active {
  display: flex;
}

.mobile-menu a {
  font-size: 1rem;
  font-weight: 500;
  color: var(--text-secondary);
  padding: 8px 0;
  transition: color var(--transition);
}

.mobile-menu a:hover {
  color: var(--text-primary);
}

/* ========================================
   Hero
   ======================================== */
.hero {
  position: relative;
  min-height: 100vh;
  display: flex;
  align-items: center;
  justify-content: center;
  overflow: hidden;
  padding-top: var(--nav-height);
}

.hero-bg {
  position: absolute;
  inset: 0;
  overflow: hidden;
}

.grid-pattern {
  position: absolute;
  inset: 0;
  overflow: hidden;
}

.grid-pattern::before,
.grid-pattern::after {
  content: '';
  position: absolute;
  border-radius: 50%;
  filter: blur(80px);
  opacity: 0.5;
  animation: drift 10s ease-in-out infinite alternate;
}

.grid-pattern::before {
  width: 600px;
  height: 600px;
  top: -10%;
  left: -5%;
  background: radial-gradient(circle, var(--gradient-start) 0%, transparent 70%);
  opacity: 0.25;
}

.grid-pattern::after {
  width: 500px;
  height: 500px;
  bottom: -10%;
  right: -5%;
  background: radial-gradient(circle, var(--gradient-end) 0%, transparent 70%);
  opacity: 0.2;
  animation-delay: -5s;
  animation-direction: alternate-reverse;
}

@keyframes drift {
  0%   { transform: translate(0, 0) scale(1); }
  50%  { transform: translate(40px, -30px) scale(1.1); }
  100% { transform: translate(-20px, 20px) scale(0.95); }
}

.hero-content {
  text-align: center;
  position: relative;
  z-index: 1;
}

.hero-badge {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 8px 16px;
  background: var(--badge-bg);
  border: 1px solid rgba(74, 222, 128, 0.2);
  border-radius: 100px;
  font-size: 0.8125rem;
  font-weight: 500;
  color: var(--badge-text);
  margin-bottom: 32px;
}

.status-dot {
  width: 8px;
  height: 8px;
  background: var(--badge-dot);
  border-radius: 50%;
  animation: pulse-dot 2s ease-in-out infinite;
}

@keyframes pulse-dot {
  0%, 100% { opacity: 1; }
  50% { opacity: 0.4; }
}

.hero-title {
  font-size: clamp(2.5rem, 6vw, 4.5rem);
  font-weight: 800;
  letter-spacing: -0.03em;
  line-height: 1.1;
  margin-bottom: 16px;
}

.gradient-text {
  background: linear-gradient(135deg, var(--gradient-start), var(--gradient-end));
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.hero-subtitle {
  font-size: clamp(1.125rem, 2.5vw, 1.5rem);
  color: var(--text-secondary);
  margin-bottom: 16px;
  font-weight: 400;
}

.hero-subtitle strong {
  color: var(--text-primary);
  font-weight: 600;
}

.hero-description {
  font-size: 1.0625rem;
  color: var(--text-tertiary);
  max-width: 560px;
  margin: 0 auto 40px;
  line-height: 1.7;
}

.hero-cta {
  display: flex;
  gap: 16px;
  justify-content: center;
  margin-bottom: 64px;
}

.btn {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 12px 28px;
  border-radius: var(--radius-sm);
  font-size: 0.9375rem;
  font-weight: 600;
  transition: all var(--transition);
  cursor: pointer;
  border: none;
}

.btn-primary {
  background: var(--accent);
  color: #fff;
  box-shadow: 0 0 0 0 var(--accent-glow);
}

.btn-primary:hover {
  background: var(--accent-light);
  box-shadow: 0 0 0 8px var(--accent-glow);
  transform: translateY(-1px);
}

.btn-ghost {
  background: transparent;
  color: var(--text-secondary);
  border: 1px solid var(--border);
}

.btn-ghost:hover {
  color: var(--text-primary);
  border-color: var(--border-hover);
  background: var(--accent-glow);
}

.hero-stats {
  display: flex;
  justify-content: center;
  gap: 64px;
}

.stat {
  display: flex;
  flex-direction: column;
  align-items: center;
}

.stat-number {
  font-size: 2rem;
  font-weight: 800;
  letter-spacing: -0.02em;
  background: linear-gradient(135deg, var(--gradient-start), var(--gradient-end));
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.stat-label {
  font-size: 0.8125rem;
  color: var(--text-tertiary);
  font-weight: 500;
  margin-top: 4px;
}

.scroll-indicator {
  position: absolute;
  bottom: 32px;
  left: 50%;
  transform: translateX(-50%);
}

.scroll-arrow {
  width: 24px;
  height: 24px;
  border-right: 2px solid var(--text-tertiary);
  border-bottom: 2px solid var(--text-tertiary);
  transform: rotate(45deg);
  animation: scroll-bounce 2s ease-in-out infinite;
}

@keyframes scroll-bounce {
  0%, 100% { transform: rotate(45deg) translateY(0); opacity: 0.6; }
  50% { transform: rotate(45deg) translateY(8px); opacity: 1; }
}

/* ========================================
   Sections
   ======================================== */
.section {
  padding: 100px 0;
}

.section-alt {
  background: var(--bg-secondary);
}

.section-title {
  font-size: 2rem;
  font-weight: 800;
  letter-spacing: -0.02em;
  margin-bottom: 48px;
  display: flex;
  align-items: center;
  gap: 16px;
}

.section-number {
  font-family: var(--font-mono);
  font-size: 1rem;
  font-weight: 500;
  color: var(--accent);
}

.section-desc {
  color: var(--text-secondary);
  font-size: 1.0625rem;
  margin-top: -32px;
  margin-bottom: 48px;
}

/* ========================================
   About
   ======================================== */
.about-grid {
  display: grid;
  grid-template-columns: 1.2fr 1fr;
  gap: 64px;
  align-items: start;
}

.about-text p {
  color: var(--text-secondary);
  font-size: 1.0625rem;
  line-height: 1.8;
  margin-bottom: 20px;
}

.about-text em {
  color: var(--accent-light);
  font-style: italic;
}

.about-highlights {
  display: flex;
  flex-direction: column;
  gap: 16px;
}

.highlight-card {
  display: flex;
  align-items: center;
  gap: 16px;
  padding: 20px;
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  transition: all var(--transition);
}

.highlight-card:hover {
  border-color: var(--border-hover);
  background: var(--bg-card-hover);
  transform: translateX(4px);
}

.highlight-icon {
  font-size: 1.5rem;
  flex-shrink: 0;
}

.highlight-card strong {
  display: block;
  font-weight: 600;
  margin-bottom: 2px;
}

.highlight-card p {
  font-size: 0.875rem;
  color: var(--text-tertiary);
}

/* ========================================
   Timeline / Experience
   ======================================== */
.timeline {
  position: relative;
  padding-left: 32px;
}

.timeline::before {
  content: '';
  position: absolute;
  left: 7px;
  top: 8px;
  bottom: 8px;
  width: 2px;
  background: var(--border);
}

.timeline-item {
  position: relative;
  padding-bottom: 48px;
}

.timeline-item:last-child {
  padding-bottom: 0;
}

.timeline-marker {
  position: absolute;
  left: -32px;
  top: 8px;
  width: 16px;
  height: 16px;
  border-radius: 50%;
  background: var(--bg-primary);
  border: 2px solid var(--border);
  z-index: 1;
}

.timeline-marker.current {
  border-color: var(--accent);
  background: var(--accent);
}

.timeline-marker.current .timeline-pulse {
  position: absolute;
  inset: -4px;
  border-radius: 50%;
  border: 2px solid var(--accent);
  animation: timeline-pulse 2s ease-in-out infinite;
}

@keyframes timeline-pulse {
  0%, 100% { opacity: 0; transform: scale(1); }
  50% { opacity: 0.5; transform: scale(1.5); }
}

.timeline-marker.edu {
  border-color: var(--accent-light);
  background: var(--accent-glow);
}

.timeline-content {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  padding: 28px;
  transition: all var(--transition);
}

.timeline-content:hover {
  border-color: var(--border-hover);
  box-shadow: 0 4px 24px rgba(0, 0, 0, 0.1);
}

.timeline-header {
  display: flex;
  justify-content: space-between;
  align-items: flex-start;
  margin-bottom: 16px;
}

.timeline-date {
  font-family: var(--font-mono);
  font-size: 0.8125rem;
  color: var(--accent);
  font-weight: 500;
}

.timeline-content h3 {
  font-size: 1.25rem;
  font-weight: 700;
  margin-top: 4px;
}

.timeline-company {
  color: var(--text-secondary);
  font-size: 0.9375rem;
  margin-top: 2px;
}

.badge {
  padding: 4px 12px;
  border-radius: 100px;
  font-size: 0.75rem;
  font-weight: 600;
  background: var(--tag-bg);
  color: var(--tag-text);
  white-space: nowrap;
}

.badge-current {
  background: var(--badge-bg);
  color: var(--badge-text);
}

.badge-live {
  background: var(--badge-bg);
  color: var(--badge-text);
}

.timeline-details {
  margin-bottom: 16px;
}

.timeline-details li {
  position: relative;
  padding-left: 20px;
  margin-bottom: 8px;
  color: var(--text-secondary);
  font-size: 0.9375rem;
  line-height: 1.6;
}

.timeline-details li::before {
  content: '▸';
  position: absolute;
  left: 0;
  color: var(--accent);
  font-weight: 700;
}

.timeline-tags, .project-tags {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
}

.tag {
  padding: 4px 12px;
  background: var(--tag-bg);
  color: var(--tag-text);
  border-radius: 100px;
  font-size: 0.75rem;
  font-weight: 500;
}

/* ========================================
   Projects
   ======================================== */
.projects-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(320px, 1fr));
  gap: 24px;
}

.project-card {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  padding: 32px;
  transition: all var(--transition);
  position: relative;
  overflow: hidden;
}

.project-card::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 3px;
  background: linear-gradient(90deg, var(--gradient-start), var(--gradient-end));
  opacity: 0;
  transition: opacity var(--transition);
}

.project-card:hover {
  border-color: var(--border-hover);
  transform: translateY(-4px);
  box-shadow: 0 12px 40px rgba(0, 0, 0, 0.15);
}

.project-card:hover::before {
  opacity: 1;
}

.project-card.featured {
  grid-column: 1 / -1;
  border-left: 3px solid var(--accent);
  background: linear-gradient(135deg, var(--accent-glow) 0%, var(--bg-card) 40%);
}

.project-card.featured::before {
  opacity: 1;
}

@media (min-width: 768px) {
  .project-card.featured {
    grid-column: 1 / -1;
    display: grid;
    grid-template-columns: auto 1fr;
    grid-template-rows: auto auto 1fr auto;
    column-gap: 32px;
  }

  .project-card.featured .project-card-header {
    grid-column: 1 / -1;
  }
}

.project-card-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 16px;
}

.project-icon {
  font-size: 2rem;
}

.project-card h3 {
  font-size: 1.25rem;
  font-weight: 700;
  margin-bottom: 12px;
}

.project-card p {
  color: var(--text-secondary);
  font-size: 0.9375rem;
  line-height: 1.7;
  margin-bottom: 16px;
}

.project-platforms {
  display: flex;
  gap: 16px;
  margin-bottom: 16px;
}

.platform {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  font-size: 0.8125rem;
  color: var(--text-tertiary);
  font-weight: 500;
}

.project-tags {
  margin-top: auto;
}

/* ========================================
   Skills
   ======================================== */
.skills-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
  gap: 32px;
}

.skill-group h3 {
  font-size: 0.875rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  color: var(--text-tertiary);
  margin-bottom: 16px;
}

.skill-items {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
}

.skill-item {
  padding: 8px 16px;
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  font-size: 0.875rem;
  font-weight: 500;
  color: var(--text-secondary);
  transition: all var(--transition);
}

.skill-item:hover {
  border-color: var(--accent);
  color: var(--text-primary);
  background: var(--accent-glow);
}

/* ========================================
   Contact
   ======================================== */
.contact-text {
  color: var(--text-secondary);
  font-size: 1.0625rem;
  line-height: 1.8;
  margin-bottom: 48px;
  max-width: 640px;
}

.contact-links {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 20px;
}

.contact-card {
  display: flex;
  align-items: center;
  gap: 16px;
  padding: 24px;
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  transition: all var(--transition);
  color: var(--text-secondary);
}

.contact-card svg {
  flex-shrink: 0;
}

.contact-card div {
  display: flex;
  flex-direction: column;
}

.contact-card span {
  font-size: 0.9375rem;
  font-weight: 600;
  color: var(--text-primary);
}

.contact-card small {
  font-size: 0.8125rem;
  color: var(--text-tertiary);
  margin-top: 2px;
}

.contact-card:hover {
  border-color: var(--accent);
  background: var(--accent-glow);
  transform: translateY(-4px);
  box-shadow: 0 8px 32px var(--accent-glow);
}

.contact-card:hover span {
  color: var(--accent-light);
}

/* ========================================
   Footer
   ======================================== */
.footer {
  padding: 40px 0;
  text-align: center;
  border-top: 1px solid var(--border);
}

.footer p {
  font-size: 0.875rem;
  color: var(--text-tertiary);
}

.footer-sub {
  margin-top: 4px;
  font-size: 0.8125rem !important;
}

/* ========================================
   Animations
   ======================================== */
.animate-in {
  opacity: 0;
  transform: translateY(24px);
  animation: fadeInUp 0.8s cubic-bezier(0.16, 1, 0.3, 1) forwards;
}

.delay-1 { animation-delay: 0.1s; }
.delay-2 { animation-delay: 0.2s; }
.delay-3 { animation-delay: 0.35s; }
.delay-4 { animation-delay: 0.5s; }

@keyframes fadeInUp {
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

/* Scroll-triggered animations */
.reveal {
  opacity: 0;
  transform: translateY(32px);
  transition: opacity 0.8s cubic-bezier(0.16, 1, 0.3, 1), transform 0.8s cubic-bezier(0.16, 1, 0.3, 1);
}

.reveal.visible {
  opacity: 1;
  transform: translateY(0);
}

/* ========================================
   Responsive
   ======================================== */
@media (max-width: 768px) {
  .nav-links {
    display: none;
  }

  .nav-mobile-toggle {
    display: flex;
  }

  .hero-stats {
    gap: 32px;
  }

  .stat-number {
    font-size: 1.5rem;
  }

  .about-grid {
    grid-template-columns: 1fr;
    gap: 40px;
  }

  .section {
    padding: 72px 0;
  }

  .section-title {
    font-size: 1.5rem;
  }

  .hero-cta {
    flex-direction: column;
    align-items: center;
    gap: 12px;
  }

  .btn {
    width: 100%;
    max-width: 280px;
    justify-content: center;
  }

  .projects-grid {
    grid-template-columns: 1fr;
  }

  .project-card.featured {
    grid-column: 1;
  }

  .contact-links {
    grid-template-columns: 1fr;
    gap: 12px;
  }

  .timeline {
    padding-left: 24px;
  }

  .timeline-marker {
    left: -24px;
    width: 12px;
    height: 12px;
  }

  .timeline::before {
    left: 5px;
  }

  .timeline-header {
    flex-direction: column;
    gap: 8px;
  }

  .skills-grid {
    grid-template-columns: 1fr 1fr;
    gap: 24px;
  }
}

@media (max-width: 480px) {
  .hero-stats {
    flex-direction: column;
    gap: 16px;
  }

  .stat {
    flex-direction: row;
    gap: 12px;
  }

  .skills-grid {
    grid-template-columns: 1fr;
  }
}